This invention relates to a wrench, and in particular it relates to a new and improved uni-directional high torque wrench.
On many occasions it is desired to operate a wrench to tighten a nut or bolt (whichever has the plurality of outwardly facing flat surfaces engagable by the wrench), in such a manner that the wrench drives the nut or bolt in one direction of rotation and slips over the faces of the nut or bolt in the opposite direction so that the wrench can be brought back for the next torque transmitting stroke without removing the wrench from the operative surfaces of the nut or bolt. (Hereinafter the term "nut" will be used, but it is understood that the term is generic to either a nut or a bolt having such plurality of axially extending radially facing tool engaging faces.) It is also known that such wrenches, referred to as uni-directional wrenches, can completely encircle the nut or can be open ended to permit the wrench to engage a nut laterally which cannot be engaged axially, e.g. if the nut is on an elongated pipe, the ends of which are not available. One type of device known heretofore for such a purpose is a ratchet wrench as shown for example in U.S. Pat. Nos. 2,537,175; 2,691,315; 2,693,123; 3,175,434. However, such ratchet wrenches have several disadvantages. Firstly, they have a relatively large number of moving parts, rendering them rather complex and costly to manufacture. Additionally, the relatively small teeth on a ratchet wrench cannot be used for high torque applications.
To provide a uni-directional wrench having higher torque possibilities, it is also known to provide a wrench, usually an open ended box wrench, including one or more wedge like elements so positioned in the wrench that in the torque transmitting position the nut urges the wedge against a stop means, preventing further movement thereof and causing the wrench to transmit torque to the nut, while in the return direction the wedge is moved out of the way, permitting the nut to turn relative to the interior surfaces of the wrench. Such devices are shown in the following U.S. patents: Randall, U.S. Pat. No. 770,699; Morrison, U.S. Pat. No. 1,308,440; Yavner, U.S. Pat. No. 2,592,781; Yavner, U.S. Pat. No. 2,646,711; Lane, U.S. Pat. No. 2,697,372; Bergland, U.S. Pat. No. 2,721,493; Blasdell, U.S. Pat. No. 2,795,160; Yavner, U.S. Pat. No. 2,855,814; Akers, U.S. Pat. No. 2,910,902; Akers, U.S. Pat. No. 2,937,551; Stambaugh et al, U.S. Pat. No. 3,023,654; Thompson, U.S. Pat. No. 3,717,054; Doan, U.S. Pat. No. 4,255,990.
While these wedge type wrenches are an improvement over conventional ratchet wrenches as a high torque uni-directional wrench, they are still subject to several disadvantages. The difficulty is that in these known devices the direction of movement of the wedge is essentially parallel to the nut face (viewing the nut and wedge in an axial direction) and this creates several problems which can be illustrated with respect to the Thompson U.S. Pat. No. 3,717,054 and the Lane U.S. Pat. No. 2,697,372. First, the structure associated with the lower portion of these wedges, i.e. the spring means and the recess in the wrench head, are relatively bulky and extend in such a direction that it would not be possible to provide a plurality of such drive means, one for each face of the nut. Secondly, during the torque application step, the torque is applied to the wedges in a highly disadvantageous manner. Specifically, the highest torque forces are applied against the weakest portions of the wrench structure. For example, in Lane the torque is applied by the top surface of wedge 14 against the surface 10. In Thompson the greatest force is applied by pin 8 against the interior of recess 16. These are relatively small surfaces for receiving such large forces, thereby raising the possibility of the tool distorting or rupturing. A third disadvantage of these known wrenches using wedges is that the force necessary to depress the wedges to their non-torque transmitting locations requires moving the wedges in a direction which forms such an acute angle with the corresponding face of the nut that such movement is difficult at best and requires the nut to move around the wedge to engage it closer to its outer end to push it into its recess. Because the position of the nut must then be moved around within the wrench, sufficient room for such movement must be provided. This additional room prevents the possibility of designing a wrench having separate wedges or other drive means engaging each one of or at least a plurality of continuous faces about the surface of the nut.
Hence, there exists a need to provide a new and improved uni-directional wrench capable of applying high torque and not having the disadvantages of previously known uni-directional wrenches.